The Mobility Function and Neuromotor Plasticity Core (RC-3) provides expertise and investigator resources to assess the multi-system neuromotor, blomeehanical, and motor behavioral factors affecting functional movement performance. RC-3 will assist and train RCDC Scholars and OAIC investigators in the design of novel rehabilitation interventions, conduct and interpretation of quantitative movement performance outcomes that are coupled to methodologies delineating the mechanisms of brain plasticity to advance the neuroscientific basis of functional recovery in older people with functional limitations. The Core supports: 1) a development project that examines the hypothesis that stabilizing responses to balance disturbances due to volitional movements primarily engage predictive and motor planning processes involving cortical and subcortical brain areas, while responses to reflexive balance disturbances due to unexpected external events primarily engage sensory feedback in the brainstem and spinal cord;2) a PES that decodes the cortical electrophyslology of gait in stroke and older controls to characterize the dynamic neuromotor plasticity of locomotion, and another that investigates effects of split belt treadmill on locomotor re-learning after stroke;and 3) RCDC Scholar who will be mentoring in biomechanics, EEG and neuroimaging methodologies to study mechanisms of balance and mobility dysfunction in older people. RC-3 collaborates across OAIC cores in nresearch working groups to advance the next generation of interventions to the community that will enhance mobility function in older adults with chronic disability. It performs quality controlled tests of gait, balance, postural control, upper limb activities, and functional tasks (Toolbox) that characterize the processes of neuromotor control and plasticity that underlie motor learning and exercise derived functional gains across OAIC interventions. During the last 5 years, RC-3 provided core services to five PES, one DP and 6 external projects, mentored 2 RCDC Scholars and advanced testing methodology in neuromotor control and neuroimaging as well as developing new intervention methodologies.